Process for removing material from substrates

ABSTRACT

A method of removing materials, and preferably photoresist, from a substrate comprises dispensing a liquid sulfuric acid composition comprising sulfuric acid and/or its desiccating species and precursors and having a water/sulfuric acid molar ratio of no greater than 5:1 onto an material coated substrate in an amount effective to substantially uniformly coat the material coated substrate. The substrate is preferably heated to a temperature of at least about 90° C., either before, during or after dispensing of the liquid sulfuric acid composition. After the substrate is at a temperature of at least about 90° C., the liquid sulfuric acid composition is exposed to water vapor in an amount effective to increase the temperature of the liquid sulfuric acid composition above the temperature of the liquid sulfuric acid composition prior to exposure to the water vapor. The substrate is then preferably rinsed to remove the material.

CROSS-REFERENCE TO RELATED APPLICATIONS

This divisional patent application is entitled to and hereby claims thebenefit of priority, under 35 U.S.C. §§120 and 121, of the filing dateof commonly-owned U.S. Nonprovisional patent application Ser. No.11/603,634, filed Nov. 22, 2006, and titled PROCESS FOR REMOVINGMATERIAL FROM SUBSTRATES, the entire contents of which are incorporatedherein by reference.

FIELD OF THE INVENTION

The present invention relates to methods for removing material fromsubstrates. More specifically, the present invention relates to removalof materials, and preferably photoresist materials, from substratesusing sulfuric acid and water vapor.

BACKGROUND OF THE INVENTION

Advances in electronic technology cause integrated circuits to be formedon substrates such as silicon wafers with ever increasing packingdensity of active components. The formation of circuits is carried outby sequential application, processing, and selective removal of variouscomponents from the substrate. Various compositions have been developedfor removal of specific classes of components from substrates insemiconductor wafer technologies. For example, a composition commonlydenoted SC-1, which contains a mixture of NH₄OH(29 wt %)/H₂O₂(30 wt%)/water at a volume ratio of about 1:1:5 (or at somewhat higherdilution ratios), is typically used to remove particles and to reoxidizehydrophobic silicon surfaces. Similarly, a composition commonly denotedSC-2, which contains a mixture of HCl(37 wt %)/H₂O₂(30 wt %)/water at avolume ratio of about 1:1:5 (or at somewhat higher dilution ratios), istypically used to remove metals. An additional composition, commonlycalled a Piranha composition, comprises H₂SO₄(98 wt %)/H₂O₂(30 wt %) ata volume ratio of about 2:1 to 20:1, and is typically used to removeorganic contamination or some metal layers.

Photoresist materials are used in many circuit manufacturing processesto assist in formation of sequential layers. In stages of themanufacturing process, these photoresist materials are often removed,preferably without substantial damage to the substrate, includingstructures formed thereon. Photoresists are conventionally removed usingorganic solvents, such as n-methyl-pyrrolidone (“NMP”), glycol ether,amine, or dimethyl sulfoxide (“DMSO”). Alternatively, photoresistmaterials have been removed using hot chemical removal with a chemicaletching agent such as sulfuric acid and hydrogen peroxide, or using dryreactive removal generally known as photoresist plasma ashing. U.S. Pat.No. 5,785,875 discloses a method for removing photoresist material bycarrying out a wet acid etch by fully submerging the wafers within anhydrous acid, and draining the etching agent from the chamber whileinserting a heated solvent vapor. The solvent is, for example acetone,alcohols, or another solvent, but preferably comprises isopropylalcohol, and is heated to the range of between about 50° C. and about100° C. Traditional wet chemical processes used to remove photoresistrely on concentrated sulfuric acid combined with hydrogen peroxide(Piranha or “Sulfuric-Peroxide Mix” or SPM) or ozone (sulfuric-ozone mixor “SOM”). Alternatively, photoresists can be removed under certainconditions by using ozone dissolved in DI water or by mixing ozone gaswith water vapor at elevated temperatures.

It would be desirable to identify alternative techniques andcompositions for treatment to remove materials, especially organicmaterials, and most especially photoresist materials from substratessuch as semiconductor wafers.

SUMMARY OF THE INVENTION

It has been determined that applying sulfuric acid and/or itsdesiccating species and precursors (e.g. sulfur trioxide (SO₃),thiosulfuric acid (H₂S₂O₃), peroxosulfuric acid (H₂SO₅),peroxydisulfuric acid (H₂S₂O₈), fluorosulfuric acid (HSO₃F), andchlorosulfuric acid (HSO₃Cl)) to photoresist coated substrates in animmersion bath environment, even at elevated temperature, is noteffective in removal of harshly treated photoresist. In view of this ithas surprisingly been found that sulfuric acid and desiccating sulfuricacid species and precursors can be effective in removing materials,especially organic materials and most especially photoresist materialsfrom the surface of substrates when a liquid sulfuric acid compositionhaving a water/sulfuric acid molar ratio of no greater than about 5:1 isexposed to water vapor in an amount effective to increase thetemperature of the liquid sulfuric acid composition above thetemperature of the liquid sulfuric acid composition prior to exposure tothe water vapor. In an embodiment of the present invention, the liquidsulfuric acid composition is exposed to water vapor in an amounteffective to increase the temperature of the liquid sulfuric acidcomposition above both (i) the temperature of the liquid sulfuric acidcomposition prior to exposure to the water vapor and (ii) thetemperature of the water vapor. In a preferred embodiment, a liquidsulfuric acid composition having a water/sulfuric acid molar ratio of nogreater than about 5:1 is exposed to water vapor in an amount effectiveto increase the temperature of the liquid sulfuric acid composition onthe substrate surface above both (i) the on-substrate temperature of theliquid sulfuric acid composition prior to exposure to the water vaporand (ii) the temperature of the water vapor. The present method isparticularly significant in the case of removal of photoresistmaterials, even in the case when the photoresist is baked onto thesubstrate or when the photoresist is heavily ion implanted, undercertain process conditions.

For purposes of brevity, liquid sulfuric acid compositions as discussedherein will be understood to comprise sulfuric acid and/or itsdesiccating sulfuric acid species and precursors, and discussionsregarding sulfuric acid contained in these liquid compositions willlikewise be understood to describe corresponding compositions comprisingsulfuric acid and/or its desiccating sulfuric acid species andprecursors. Examples desiccating sulfuric acid species and precursors ofsulfuric acid include sulfur trioxide (SO₃), thiosulfuric acid (H₂S₂O₃),peroxosulfuric acid (H₂SO₅), peroxydisulfuric acid (H₂S₂O₈),fluorosulfuric acid (HSO₃F), and chlorosulfuric acid (HSO₃Cl). In anembodiment of the present invention, a desiccating species of sulfuricacid is a complex of sulfuric acid with an oxidizing agent.

In the method of removing materials, preferably organic materials andmore preferably photoresist, from a substrate as provided herein, asubstrate having material on a surface thereof is placed in a treatmentchamber. A liquid sulfuric acid composition is dispensed onto thesubstrate in an amount and manner effective to substantially uniformlycoat the substrate surface. For purposes of the present invention, thewater/sulfuric acid molar ratio is calculated for compositionscomprising the desiccating sulfuric acid species and precursors based onthe molar ratio in the final mixture of water to the moles present ofthe desiccating sulfuric acid species or precursor.

In one embodiment of the present invention, the substrate is pretreatedwith a pretreatment liquid to facilitate providing a surface wherein aliquid sulfuric acid composition having water/sulfuric acid molar ratioof no greater than about 5:1, when applied to the surface, willsubstantially uniformly coat on the surface. For purposes of the presentinvention, a liquid sulfuric acid composition is considered tosubstantially uniformly coat the substrate if, when sufficient liquidsulfuric acid composition is applied to the surface to completely coatthe surface, substantially no beading up of the liquid sulfuric acidcomposition (i.e. no discontinuities of the liquid on the surface) isobserved. The pretreatment composition in one embodiment comprisesapplication of sufficient liquid sulfuric acid composition havingwater/sulfuric acid molar ratio of no greater than about 5:1 to modifythe surface characteristics of the substrate, so that a subsequent (orcontinuing) application of liquid sulfuric acid composition havingwater/sulfuric acid molar ratio of no greater than about 5:1 willsubstantially uniformly coat the substrate. Optionally, other surfacemodifying components may be used in the pretreatment liquid, such assurfactants or solvents that act to modify the surface characteristicsof the substrate as desired.

In another aspect of the present invention, it has been found that theeffectiveness and efficiency of removal of materials from the surface ofa substrate is particularly enhanced wherein the liquid sulfuric acidcomposition has a water/sulfuric acid molar ratio of no greater thanabout 3:1, or no greater than about 2:1. In a preferred embodiment ofthe present invention, it has been found that the effectiveness andefficiency of removal of materials from the surface of a substrate isparticularly enhanced wherein the liquid sulfuric acid compositionhaving a water/sulfuric acid molar ratio of no greater than about 1:2.In an embodiment of the invention, the liquid sulfuric acid compositiondoes not contain water. For ease in obtaining materials, however, andembodiment of the invention contemplates that the liquid sulfuric acidcomposition will contain at least as much water as is conventionallypresent in the raw materials. In another embodiment of the presentinvention, the liquid sulfuric acid composition has a water/sulfuricacid molar ratio of from about 1:2 to about 1:4.

Stated another way, preferably the liquid sulfuric acid has aconcentration by volume greater than about 50 vol %, more preferablygreater than 80 vol %, and most preferably greater than 90 vol %. Forpurposes of the present invention, when volume ratios of sulfuric acidare discussed, it is intended that the content of sulfuric acid iscalculated based on 98 wt % sulfuric acid source. Thus, a sulfuricacid/water composition comprising sulfuric acid in a content of 50% byvolume comprises 50 vol % of 98 wt % sulfuric and 50 vol % water.

Preferably, the substrate is heated to a temperature of at least about90° C., either before, during or after dispensing of the liquid sulfuricacid composition. The liquid sulfuric acid composition is exposed towater vapor in an amount effective to increase the temperature of theliquid sulfuric acid composition on the substrate surface above thetemperature of the liquid sulfuric acid composition prior to exposure tothe water vapor. In an embodiment of the present invention, the liquidsulfuric acid composition is exposed to water vapor in an amounteffective to increase the temperature of the liquid sulfuric acidcomposition on the substrate surface above both (i) the temperature ofthe on-substrate liquid sulfuric acid composition prior to exposure tothe water vapor and (ii) the temperature of the water vapor. Eitherafter or between steps of the above described treatment, the substrateis preferably rinsed.

It has been found that the amount of water present in the liquidsulfuric acid composition prior to or as applied to the substrate isimportant to the effectiveness of the removal of undesired material.Specifically, it has been found that sulfuric acid compositions thatinitially contain too much water are less able to strip resist whenexposed to water vapor. While not being bound by theory, it is believedthat these diluted sulfuric acid compositions are either less able totake up water vapor in an amount effective to increase the temperatureof the liquid sulfuric acid composition above the temperature of theliquid sulfuric acid composition prior to exposure to the water vapor,or the chemical activity of the composition is decreased by the water,or both.

In embodiments where the substrate is at an ambient processingtemperature below the boiling point of water (particularly in atemperature range of about 20-60° C.), the temperature of the liquidsulfuric acid composition is substantially increased upon addition ofwater vapor. Surprisingly, it further has been found that even when thesubstrate and/or the sulfuric acid composition is at a high temperature(e.g. greater than about 90° C.), and particularly at a temperature ator above 100° C., the water vapor is taken up by the liquid sulfuricacid composition even though the temperature of the liquid sulfuric acidcomposition is near or above the boiling point of water. While not beingbound by theory, it is believed that the liquid sulfuric acid has adesiccating effect, thereby causing water from the water vapor to becondensed into the liquid sulfuric acid composition and releasing theenergy corresponding roughly to the heat of vaporization stored in thewater vapor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing the resulting temperature rise when liquidwater or H₂O₂ (30 wt %) is added to H₂SO₄ (98 wt %).

FIG. 2 is a graph showing the temperature rise when liquid water isadded to a blend of H₂SO₄ (98 wt %)/water as a function of the fractionof H₂SO₄ (98 wt %) in the solution.

FIG. 3A shows a schematic view of a batch spray processor that can beused to carry out the process of the present invention.

FIG. 3B shows one representative mode of practice of using the processorshown in FIG. 1A.

FIG. 4 is graph showing the temperature of the liquid composition ofsulfuric acid/hydrogen peroxide as cast onto the side wall of theprocessing chamber during runs of a comparative process and of a processof the present invention.

FIG. 5 is a graph showing the maximum measured on-wafer temperatures ofthe sulfuric acid/hydrogen peroxide composition during runs of acomparative process, and after exposure to water vapor in a process ofthe present invention. Also shown are the temperatures of the sulfuricacid/hydrogen peroxide compositions as blended, before being dispensed.

FIG. 6 is a graph showing the difference between the maximum measuredon-wafer temperatures of the sulfuric acid/hydrogen peroxide compositionafter exposure to water vapor and the temperature of the sulfuricacid/hydrogen peroxide compositions as blended during runs of acomparative process, and of a process of the present invention. Alsoshown are the averaged temperatures of the sulfuric acid/hydrogenperoxide composition as blended, before being dispensed.

FIG. 7 shows a schematic view of a single-wafer processor that can beused to carry out the process of the present invention.

FIG. 8 shows a system for directing a spray using a three orificenozzle.

DETAILED DESCRIPTION

The above mentioned and other advantages of the present invention, andthe manner of attaining them will become more apparent, and theinvention itself will be better understood by reference to the followingdescription of the embodiments of the invention taken in conjunctionwith the accompanying drawings.

For purposes of the present invention, water vapor is defined as waterin the gaseous form, and distinguished from small droplets of watercommonly called “mist.” Because mist is water that is condensed in theform of small droplets, there is essentially no net warming effect whenmist settles on a surface that would correspond to a heat ofvaporization. For purposes of the present invention, steam is vaporizedwater at or above the boiling point of water, which depends on thepressure, e.g. 100° C. if the pressure is 1 atmosphere. When steam isprovided at a temperature greater than the boiling point of water, is itcalled superheated steam. Water vapor optionally may be provided fromcompositions comprising components in addition to water, such asdissolved gasses such as ozone, or inert gasses such as nitrogen. It iscontemplated that water vapor may be supplied to the sulfuric acidcomposition in any manner, either essentially pure, or in compositions,either above, or below or at 100° C., and having pressures or partialpressures of water vapor either above, below or at 1 atm.

The method of the present invention may be used to process multiplewafer-like objects simultaneously, as occurs with batches of wafers whenbeing processed in a spray processing tool such as the MERCURY® or ZETA®spray processors commercially available from FSI International, Inc.,Chaska, Minn., or the Magellan® system, also commercially available fromFSI International, Chaska, Minn. The present invention may also be usedin single wafer processing applications where the wafers are eithermoving or fixed, or in batch applications where the wafers aresubstantially stationary.

With reference to the figures, wherein like numerals are used to labellike components throughout the several figures:

FIG. 1 shows the resulting temperature when 20° C. H₂SO₄(98 wt %) ismixed with 20° C. liquid water or 20° C. H₂O₂(30 wt %) in a rapidlystirred beaker. In region A, at H₂SO₄ volume fractions betweenapproximately 100% and 57%, the H₂SO₄/water blend increases intemperature with increasing water content. In region B, at fractionsbetween approximately 56% and 36%, the H₂SO₄/water blend decreasesslowly in temperature with increasing water content. In region C, atfractions between approximately 35% and 10%, the temperature of theblend decreases rapidly with increasing water content. The temperatureprofile of H₂SO₄ mixed with H₂O₂ follows the same trend, but with aslightly lower maximum temperature. A maximum temperature rise ofapproximately 1100 (130° C. final temperature) is obtained with anH₂SO₄/water blend that is a blend of approximately 57 vol % H₂SO₄ and 43vol % H₂O₂. Also shown on the top axis is the H₂O to H₂SO₄ mole ratio ofthe water:H₂SO₄ blend. The boundaries between regions A and B isapproximately 2:1 water:H₂SO₄, and between B and C is approximately 5:1.

FIG. 2 shows the derivative of the water-added curve from FIG. 1. Thisshows the rise in temperature for each percent increase in water contentas a function of the fraction of H₂SO₄ in the solution. There is analmost linear decrease in dT/dWater from 100% to 37% H₂SO₄ fraction.While not being bound by theory, it is believed that the temperatureincrease of the solution (the heat of mixing) is being caused by theheat of hydration as water molecules coordinate around each sulfuricacid molecule. In the present invention, this strong attraction betweenthe water and sulfuric molecules drives the desiccant action that drawswater vapor from the atmosphere and into the sulfuric acid composition,even when the temperature of the sulfuric acid composition is above theboiling point of water. At approximately 55 vol % sulfuric acid, theheat of hydration is balanced by the thermal load of the added water,and additional added water has a net cooling effect on the blend. Atapproximately 37 vol % H₂SO₄, the hydration of H₂SO₄ appears to becomplete. As shown in the upper x-axis of FIGS. 1 and 2 show the moleratio of water:H₂SO₄ in the solution. The hydration appears to becomplete when approximately 5 moles of water are present for each moleof H₂SO₄.

In contrast to FIG. 1, the present invention adds water to the sulfuricacid composition by condensation of water vapor into the composition.This results in the heating of the composition not only by the heat ofmixing between H₂SO₄ and H₂O, but also by the water's heat ofvaporization that is regained when the water condenses into the sulfuricacid composition. Compared to adding liquid water to H₂SO₄, the thermalcontribution from water vapor's heat of vaporization allows largertemperature increases for a given amount of dilution.

FIGS. 3A and 3B show one example of equipment useful for carrying outthe process of the present invention. FIG. 3A shows a schematic view ofa batch spray processor 10 showing main system components includingchemical mixing manifold 90, recirculation tank 50, and process bowl 12,The equipment 10 is a schematic representation of a spray processingtool such as that included in a MERCURY® or ZETA® spray processorcommercially available from FSI International, Inc., Chaska, Minn.Equipment 10 generally includes a bowl 12 and lid 14 defining aprocessing chamber 16. Wafer-like objects 18 are positioned in carriers20 (e.g., TEFLON® cassettes), which in turn are held upon rotatingturntable 22 by turntable posts (not shown). Turntable 22 is coupled tomotor-driven shaft 24. Water or nitrogen may be supplied from supplyline(s) 32 and dispensed into processing chamber 16 through theturntable posts (not shown). One or more chemicals may also be suppliedfrom supply line(s) 34 and dispensed into processing chamber 16 directlyonto the wafers 18 and/or directly onto turntable 22 through centerspray post 36 or onto the wafers via the side spray post 40 via line(s)38.

For example, a supply line 34 can be fluidly coupled to a chemicalrecirculation system 49. The recirculation system can include chemicalsupply lines 67 and 68. Chemical supply line 67 can include filters 64and 66, pump 62, and be fluidly coupled to recirculation supply tank 50.The recirculation supply tank can be supplied with process chemical fromrecirculation drain 54 and fresh chemical makeup 52. A nitrogen blanket56 can be used in the headspace of tank 50. To control temperature ofthe process chemical in tank 50, tank 50 can include a heating coil 58,cooling coil 60, and temperature probe 41. Chemical supply line 68 cansupply, e.g., nitrogen and DI water rinse. After supplying chemical toprocessing chamber 16, any unused chemical can enter drain 70 and passinto drain manifold 71. From the drain manifold, the chemical can bedirected to a variety of outlets such as recirculation drain 54, exhaust72, DI drain 74, auxiliary 76, auxiliary 78, auxiliary 80, and auxiliary82.

Supply line 34 can also be fluidly coupled to a fresh chemical blendingmanifold 90. In the manifold, controlled flows of fresh chemicals fromlines 91-94 are mixed to form a desired blend that is sent to the centerspray post 36 via line(s) 98 and 34 or to the side spray post 40 vialines 98 and 38. Optionally, the chemical blend can be heated by anin-line infra-red heater in line 98 (heater not shown). Alternately, oneor more of the feed chemicals can be heated by an infra-red heaterplaced in one or more of lines 91-94.

The configuration and use of equipment 10 has been further described inU.S. Pat. Nos. 5,971,368; 6,235,641; 6,274,506; and 6,648,307, as wellas in Assignee's co-pending U.S. patent application titled ROTARYUNIONS, FLUID DELIVERY SYSTEMS, AND RELATED METHODS in the names ofBenson et al., filed Mar. 12, 2004, and having U.S. Ser. No. 10/799,250,said co-pending application being incorporated herein by reference inits entirety.

FIG. 3B shows one representative mode of practice of using the equipment10 in accordance with the present invention. A liquid sulfuric acidcomposition 42 is dispensed onto wafers 18 from center spray post 36and/or side spray post 40 (not shown) in an amount effective tosubstantially uniformly coat the organic material coated substrate. Thissubstantially uniform coating may be facilitated by pretreatment, forexample, using the same apparatus, with a pretreatment liquid to providea surface wherein a liquid sulfuric acid composition havingwater/sulfuric acid molar ratio of no greater than about 5:1, whenapplied to the surface, will substantially uniformly coat on thesurface. As noted above, the pretreatment composition may for example bea preapplication of liquid sulfuric acid composition to modify thesurface characteristics of the substrate, so that a subsequent (orcontinuing) application of liquid sulfuric acid composition havingwater/sulfuric acid molar ratio of no greater than about 5:1 willsubstantially uniformly coat the substrate. Optionally, other surfacemodifying components may be used in the pretreatment liquid, such assurfactants or solvents that act to modify the surface characteristicsof the substrate as desired. Additional components may be added toprovide chemical modification of the pretreatment solution. For example,a minor amount of acid may be added to an aqueous pretreatment solution.

After (or while, or before) the liquid sulfuric acid composition 42 isdispensed, hot water 44 is dispensed onto turn table 22. Evaporation ofa portion of the hot water 44 increases the water vapor content(humidity) of the chamber atmosphere. Wafers 18 have been coated with anorganic material that is to be removed. In preferred embodiments, theorganic material is photoresist material. Organic materials that arechallenging to remove include photoresist that has been baked on byexposure to heat during previous wafer processing steps. Organicmaterials that are particularly challenging to remove are those thathave been heavily ion implanted during previous wafer processing steps.The methods of the present invention are particularly and surprisinglyeffective in the removal of heavily ion implanted photoresist materials.

The liquid sulfuric acid composition 42 has a water/sulfuric acid molarratio of no greater than about 5:1. Thus, the liquid sulfuric acidcomposition is limited in water content. In one embodiment, the liquidsulfuric acid composition may comprise a solvent that does notsubstantially interfere with the coordination of subsequently addedwater vapor with sulfuric acid, as discussed in more detail herein.Preferred such solvents are inert with respect to the substrate to betreated (e.g. the wafer), such as fluorine based liquids. An example ofsuch inert solvents include the Fluorinert™ solvents commerciallyavailable from 3M, St. Paul, Minn. It should be noted that the abovementioned molar ratio recites the water/sulfuric acid molar ratio, andnot the solvent/sulfuric acid ratio. This underscores that the solventthat does not substantially interfere with the coordination ofsubsequently added water vapor with sulfuric acid does not factor intothis ratio of the present inventive embodiment.

More preferably, the liquid sulfuric acid composition is highlyconcentrated. Preferably, the liquid sulfuric acid composition isdispensed at a sulfuric acid concentration of at least about 80 vol %,more preferably at least about 90 vol %, and most preferably at leastabout 94 vol %. As shown in FIGS. 1 and 2, these high H₂SO₄concentrations result in the largest temperature rise per unit of watervapor condensed into the H₂SO₄ composition.

In an embodiment of the present invention, the liquid sulfuric acidcomposition 42 comprises hydrogen peroxide. The hydrogen peroxide servesas an oxidant that assists in breaking down organic species to CO₂ andwater. Hydrogen peroxide is conveniently provided in a water-containingsolution blended with concentrated sulfuric acid to provide a liquidsulfuric acid composition having water/sulfuric acid molar ratio of nogreater than about 5:1. Advantageously, mixing of concentrated sulfuricacid with a water-containing hydrogen peroxide solution generates heatby an exothermic reaction, and so the resulting liquid sulfuric acidcomposition comprising hydrogen peroxide can be provided at elevatedtemperature while using less energy from a dedicated heat source to heatthe composition. This exothermic reaction is normally a significantsource of heat for the composition, However, in the present inventionthe reaction between the sulfuric acid composition and water vaporprovides the desired heat, and excess additions of water-based hydrogenperoxide can inhibit this sulfuric-vapor reaction. Therefore, with theknowledge of the effect of vapor in concentrated sulfuric acidcompositions as described herein, the skilled artisan can now adjust theH₂O₂ concentration to simultaneously optimize the heat generated by theH₂SO₄-vapor reaction while supplying sufficient reactants to oxidizeorganics.

In an aspect of the present invention, an oxidizing agent can beintroduced into the treatment chamber before, during or after dispenseof the liquid sulfuric acid composition.

For example, hydrogen peroxide can be mixed with the liquid concentratedsulfuric acid prior to introduction of the liquid sulfuric acidcomposition into the treatment chamber, or alternatively during or afterdispense of the liquid sulfuric acid composition in the treatmentchamber. Mixing of the hydrogen peroxide with the liquid concentratedsulfuric acid can be accomplished by the use of static mixers or activemixing techniques, or can be merely contacting one solution with theother, with mixing being accomplished by mere diffusion. Other agents,such as ozone, may be similarly incorporated in the liquid sulfuric acidcomposition as desired. Water-free oxidants such as ozone may besuperior to H₂O₂ as they will not dilute the H₂SO₄ composition. Forexample, oxidants other than H₂O₂ may be utilized in the inventivesulfuric-vapor process. For instance, ozone, nitric acid, the chromateion (Cr⁺⁶), or the ceric ion (Ce⁺⁴) may be incorporated in the processas described herein. In particular, these species might be added toH₂SO₄ in an anhydrous form, so that the H₂SO₄ remains relativelyundiluted. Other oxidants may also be used.

Preferably, the liquid sulfuric acid composition is dispensed at atemperature of at least about 90° C., and more preferably from aboutfrom about 90° C. to about 150° C. In another embodiment, the liquidsulfuric acid composition is preferably dispensed at a temperature offrom about 95° C. to about 120° C. In another embodiment, the liquidsulfuric acid composition is dispensed at a temperature of at leastabout 130° C. prior to exposure to the water vapor, and more preferablyfrom about 130° C. to about 200° C.

The introduction of the liquid sulfuric acid composition 42 wets thewafer surfaces with the sulfuric acid chemistry. Preferably liquidsulfuric acid composition 42 is applied to the wafer in an amount toprovide sufficient sulfuric acid functionality to remove the organicmaterial coated on wafer 18. Preferably, the liquid sulfuric acidcomposition is dispensed onto the organic material coated substrate to athickness of at least about 5 microns, more preferably to a thickness ofat least about 10 microns. In an embodiment of the present invention,the liquid sulfuric acid composition is dispensed onto the organicmaterial coated substrate to a thickness of from about 10 microns toabout 140 microns, and preferably to a thickness of from about 10microns to about 60 microns.

In one embodiment, wafers 18 are provided at a temperature below theboiling point of water, such as at a temperature of from about 20 toabout 60° C. Wafers 18 are preferably heated to a temperature of atleast about 90° C., either before, during or after dispensing of theliquid sulfuric acid composition. More preferably, wafers 18 are heatedto a temperature of from about 90° C. to about 150° C. In anotherembodiment, the wafers are heated to a temperature of from about 95° C.to about 120° C. This heating can be carried out, for example, byheating the chamber using radiant heat, introduction of hot water orother liquid solution to the wafer with substantial removal of theheated liquid prior to application of the concentrated sulfuric acidcomposition, introduction of heated gases to the chamber, and the like.If a liquid is used to heat the wafer by direct contact to the wafer,sufficient amount of the liquid is removed from the wafers prior tointroduction of the concentrated sulfuric acid composition so that theconcentrated sulfuric acid composition maintains the desired level ofsulfuric acid concentration prior to the exposure of the liquid sulfuricacid composition to water vapor.

In one embodiment of the present invention, the wafers can be preheatedby submerging one or more wafers into a heated bath of liquid, quicklydraining the contents of the bath (e.g. a “quickdump” procedure) andconducting the remaining treatment steps as described below. The bathliquid can be, for example, DI water, DI water containing sulfuric acid,sulfuric acid/hydrogen peroxide mixture, an inert fluid (such as afluorocarbon), sulfuric acid/ozone mixture, and the like. Thisembodiment can provide substantial benefit in enhancing throughput ofthe treatment process by more efficiently heating the wafers. An exampleof a particularly suitable process system that can be used to employthis embodiment is the Magellan® system commercially available from FSIInternational, Chaska, Minn.

Water vapor is introduced to the chamber in any appropriate manner. Asshown in FIG. 3B, heated DI water 44 is splashed down onto the rotatingturntable 22 from the bottom 46 of center spray post 36. In this“splashdown” approach, water vapor is generated. Alternatively, watervapor can be generated inside the treatment chamber by any appropriatealternative water vapor generation technique, such as by heating and/oragitating water in the treatment chamber.

In yet another alternative, the water vapor can be generated outside ofthe treatment chamber and introduced to the treatment chamber in thedesired water vapor form.

For instance, externally produced water vapor could be supplied to thechamber as a gas, or as component of a mixture of gasses. In oneembodiment, vapor could be produced by bubbling a gas (eg. N₂) through acolumn of water (preferably hot water). In another embodiment, the gascould pass over the surface of a quantity of water. In anotherembodiment, the gas could pass through an irrigated packed column ascommonly used in chemical engineering. In another embodiment,substantially pure water vapor could be produced by boiling liquidwater. The gaseous products from any of these alternatives could befurther heated. Other embodiments are also possible.

Preferably, the water vapor is introduced so that it is exposed to thewafers at a water vapor temperature of from about 70° C. to about 150°C. More preferably, the water vapor is introduced so that it is exposedto the wafers at a water vapor temperature of from about 80° C. to about110° C. In a particularly advantageous embodiment, the water vapor isintroduced so that it is exposed to the wafers at a water vaportemperature of from about 85° C. to about 98° C. This embodiment isadvantageous because the water vapor is easy to generate by the“splashdown” approach described above. Because the water is not at theboiling point, control of entry of the stream of water without unduespattering is easier to accomplish. In different advantageousembodiment, the water vapor is introduced so that it is exposed to thewafers at a water vapor temperature of about 100° C. This embodiment isrelatively easy to carry out by boiling water under conventionalconditions to form steam either inside or outside the treatment vesselby conventional steam forming apparatus.

In another embodiment, the water vapor is provided at a temperaturegreater than the temperature of the liquid sulfuric acid compositionprior to exposure to the water vapor. This embodiment provides thebenefit of direct heating of the liquid sulfuric acid composition bydirect heat transfer, as well as the transfer of energy uponcondensation of the water vapor into the liquid sulfuric acid asdiscussed above. In an embodiment, the water vapor is provided at atemperature greater than about 150° C. for this purpose.

Optionally, the water vapor can additionally comprise another agent,such as hydrogen peroxide or ozone, as desired.

The water vapor is introduced into the treatment chamber in an amounteffective to increase the temperature of the liquid sulfuric acidcomposition above the temperature of the liquid sulfuric acidcomposition prior to exposure to the water vapor, and preferablyadditionally above the temperature of the water vapor. In an embodimentof the present invention, the liquid sulfuric acid composition isexposed to water vapor in an amount effective to increase thetemperature of the liquid sulfuric acid composition on the substratesurface above both (i) the temperature of the on-substrate liquidsulfuric acid composition prior to exposure to the water vapor and (ii)the temperature of the water vapor. Surprisingly, even when thetemperature of the liquid sulfuric acid composition is near or evenabove the boiling point of water, the water vapor still associates withthe liquid sulfuric acid composition in a manner to increase thetemperature of the liquid sulfuric acid composition, thereby enhancingthe organic material removing effectiveness of the increase thetemperature of the liquid sulfuric acid composition.

Preferably, sufficient liquid sulfuric acid composition and water vaporare present and mixed to increase the temperature of the liquid sulfuricacid composition by at least about 20° C., more preferably by at leastabout 40° C., and more preferably by at least about 60° C. This isparticularly significant since the liquid sulfuric acid composition isin place on the wafer, which itself acts as a heat sink and absorbssubstantial energy to maintain a temperature that is close to thetemperature of the liquid sulfuric acid composition. The temperature ofthe liquid sulfuric acid composition on the substrate surface can bedetermined by any appropriate measuring technique. For purposes of thepresent invention, an appropriate temperature approximation can be madeby using temperature probe 41 to measure the temperature of liquid castonto the treatment vessel walls during spinning of the wafer carriers onturntable 22. To carry out this measurement, a temperature probe may bepositioned within the treatment vessel. In one embodiment, acolor-changing temperature indicating material may be used to indicatethe maximum temperature reached in the treatment vessel.

The exposure of the liquid sulfuric acid composition to water vapor canbe carried out at any time effective to increase the temperature of theliquid sulfuric acid composition when in place on the organic materialcoated substrate. In one embodiment, water vapor is introduced to thetreatment chamber during the dispense of the liquid sulfuric acidcomposition. It will be appreciated that in this embodiment, thetemperature of the liquid sulfuric acid composition may begin toincrease even prior to contact of the composition with the substrate. Inthis embodiment, the increase of the temperature of the liquid sulfuricacid composition upon exposure to water vapor as discussed above can betaken to be the difference between the temperature of the liquidsulfuric acid composition at dispense and the maximum temperature of theliquid sulfuric acid composition after exposure to water vapor.

In another embodiment of the present invention, the liquid sulfuric acidcomposition is provided to the wafers not in a continuous stream, butrather in a plurality of discrete pulses. These pulses are preferablyshort (i.e. from about 3-10 seconds in length), and at high flow (i.e.at a flow rate of about 2-8 lpm). There preferably is a time period ofabout 5 to 20 seconds between pulses with no flow of liquid. Whenoperating with pulsed liquid flow, water vapor optionally is onlyintroduced during the pulse, reducing the amount of water vapor that isflushed from the chamber during the present process. Likewise, watervapor can be optionally introduced during the pulse, to enhance thetemperature rise of the sulfuric acid composition before its contactwith the substrate, or between pulses, to emphasize the heating of thecomposition while on the substrate.

In another embodiment, the dispense of the liquid sulfuric acidcomposition is stopped prior to introduction of the water vapor. In anaspect of this embodiment, the substrate is provided with a coating ofthe liquid sulfuric acid composition that is relatively stagnant.Optionally, rotation of the substrate is slowed to a rate of less thanabout 20 rpm or stopped during and/or after dispense of the liquidsulfuric acid composition, and during exposure of the liquid sulfuricacid composition to the water vapor. This process is carried out topromote maintenance of this coating (or “pooling”) of liquid sulfuricacid composition on the substrate. While not being bound by theory, itis believed that because the liquid sulfuric acid composition exhibitslittle bulk motion especially during exposure of the liquid sulfuricacid composition to the water vapor, the liquid tends to dissolve and/orotherwise remove the undesired materials on the surface of the substrateat a comparable rate across all points on the substrate. This enhanceduniformity may be due to uniform exposure of the liquid sulfuric acidcomposition to the water vapor. Additionally or alternatively, theenhanced uniformity of removal of undesired material (in particular,removal of SiO₂) may be due to uniform saturation rates of the liquidsulfuric acid composition by the dissolved undesired material across thecoating. The dispense of the liquid sulfuric acid composition mayfurther be modified by varying the thickness of the liquid sulfuric acidcomposition layer by varying the flow rate, dispense time, and the rateof removal of the liquid sulfuric acid composition by centrifugal force.Further, the aggressiveness of removal of undesired material may beincreased by ramping off the spent sulfuric acid solution mixture afterthe vapor step, applying a fresh layer of sulfuric acid solutionmixture, and re-introducing vapor into the chamber.

As noted above, the liquid sulfuric acid composition 42 is dispensedonto wafers 18 from spray posts 36 and/or 40. In certain configurationsof wafer treatment equipment, positioning of the spray posts anddirection of flow of fluid from the posts have been found to impact theperformance of the present process. In certain wafer treatment apparatihaving a fixed spray post configuration, dispensed fluid tends to bedeposited in a manner leading to heavy concentrations of liquid atportions of the wafer. For example, liquids dispensed from the centerspray post 36 tend to be deposited on the substrate at heavyconcentrations near the center spray post. Also, at some orientations ofthe turntable 22, a large fraction of the liquid from the center spraypost can pass between the wafers and be wasted. Advantageously, superiordeposition efficiency and uniformity can be achieved by using theside-bowl spray post 40 (SBSP.) But spray dispensed by the SBSP normalto the face of the chamber, directly toward the turn table's axis ofrotation, also tends to deposit liquid excessively near the center spraypost. The normal spray further wastes liquid that passes between thewafers at some orientations of the turn table. Superior depositionpatterns may be observed by angling the spray of liquids from the sprayposts (and particularly the SBSP) off normal from the major surface ofthe chamber and/or away from the center of the turntable. While angledspray results in a less “focused” deposition near the CSP, no individualangle suffices for uniform coverage. The angle of spray in an embodimentof the invention is stationary. In another embodiment of the invention,the turntable holding the substrate(s) is rotating during dispense ofthe liquid sulfuric acid composition onto the surface of the substrate,and the liquid sulfuric acid composition is dispensed by spraying theliquid at a varying angle relative to the turntable in a sweepingmotion. In one aspect of this embodiment, the angle of spray variesduring a single dispense of the liquid sulfuric acid composition. Inanother aspect of this embodiment, the angle of spray varies from onedispense of the liquid sulfuric acid composition to the next when aplurality of liquid dispenses are carried out in a treatment cycle.

Varying the angle of spray of the liquid sulfuric acid composition (or“sweeping”) results in varying the location of the spray's focus,leading to more uniform liquid deposition. Varying the spray's angle ofincidence on the wafer-carrier system also reduces the effects ofshadowing by structural members of the cassette and turntable. It ispossible to vary the angle of the spray in many ways including, forinstance, rotating the spray mechanism or spraying through multiplespray mechanisms at varying angles.

A preferred method and apparatus of varying the direction of the SBSP's40 spray is shown in FIG. 8, which shows a system 120 for directing aspray using a three orifice nozzle 122. In this nozzle, a centralorifice 124 is provided with liquid from a liquid source (not shown)under sufficient pressure to eject a stream 126 of liquid therefrom. Gasorifice 130 is provided with a gas from gas source 134 through controlvalve 136. The gas is provided at a regulated pressure to eject a streamof gas 138 from orifice 130 that simultaneously deflects and atomizesthe spray. Similarly, gas orifice 140 is provided with a gas from gassource 144 through control valve 146. The gas is provided at a regulatedpressure to eject a stream of gas 148 from orifice 140 thatsimultaneously deflects and atomizes the spray. The spray direction canbe adjusted by modifying the flow of gas streams 138 and 148 to impart adirection to the flow of the liquid spray. Finer gradations of gas flowallow finer adjustment of the spray direction. Equal flows from the twogas sources result in a spray pattern centered perpendicular to the faceof the spray mechanism. The spray can be deflected discretely (e.g. 10seconds at +20°, then 10 seconds at +30°, etc.), or swept continuously.The gas flows can be modulated over a continuous range, such as by massflow controllers, or discretely, as by multiple orifices. This system120 is particularly advantageous for use in treatment of semiconductorwafers, because it provides excellent directional and force control ofspray of liquid. Furthermore, this excellent control is provided withoutthe need to install an apparatus having moving parts in the treatmentchamber. The minimization of the amount of moving parts in treatmentchambers is desirable because moving parts increases the likelihood ofintroduction of small particles in the chamber due to frictional wear ofmoving components. Additionally, service of equipment is greatlysimplified if the equipment is not located in the treatment chamber.

In the case of either stationary or sweeping spray introduction ofliquid sulfuric acid composition into the treatment chamber, thedirection of the spray preferably is coordinated with the rotation ofthe substrates in the chamber. In an embodiment of the presentinvention, spray is angled into the oncoming wafers as they rotate inthe chamber on a turntable. That is, the spray from the side-bowl spraypost 40 is deflected to the right during clockwise rotation of theturntable and left during counterclockwise rotation.

In another embodiment of the present invention, the effects of shadowingby structural members of the cassette and turntable and/or theoverconcentration of liquid at certain locations in the chamber can beameliorated by placement of deflecting members in the chamber tointerrupt or block the flow of the spray in certain directions. Thesemembers can be supported by the bowl 12 or lid 14 and thus besubstantially stationary, or can be supported by the turntable 22, andthus be at a substantially fixed location with respect to the rotatingwafers.

In embodiments of the present invention, it is contemplated that thesubstrate may be pretreated to assist in removal of the organic materialtherefrom. For example, the substrate having organic material coated ona portion thereof can be treated with a surfactant-containingcomposition prior to dispensing the liquid sulfuric acid compositionthereon.

Additional manipulation steps are also contemplated during the describedmethod, such as exposure of the substrate to megasonic energy before,during or after treatment by the liquid sulfuric acid composition.

An apparatus for use in the present method can be prepared by modifyinga known programmable spray processing machine such as a centrifugalspray processor of the type commercially available from FSIInternational, Chaska, Minn., under one or more of the tradedesignations MERCURY® or ZETA®, by providing the chemical reservoirsthereof with the necessary solutions and by configuring the machine'scontroller with a program as indicated herein. It will be understoodthat other known batch spray and single wafer spray machines cansimilarly be modified to carry out the present invention.

In another embodiment, the inventive process could also be applied toone wafer at a time in a “single wafer” mode. FIG. 7 shows oneembodiment of such a single wafer process apparatus 100 with a sulfuricacid composition 102 being dispensed on a wafer 103 from a duct 101 asthe wafer is supported on a holding chuck (not shown) mounted on theshaft of a motor 104. Water vapor 105 is introduced through duct 106.The apparatus is in a chamber 107 sufficiently closed such that thedesired levels of vapor can be maintained at the wafer surface.

In one embodiment, apparatus 100 can be operated with a continuousdispense of sulfuric acid composition from duct 101, with duct 101either stationary or moving relative to wafer 103. Vapor can beintroduced into the apparatus either before, during, or after the startof the dispense.

In another embodiment, the entire wafer is wetted with the sulfuric acidcomposition and the dispense stopped, allowing the composition to form afilm on the wafer of relatively uniform thickness. In this embodiment,the wafer can be provided with a coating of the liquid sulfuric acidcomposition that is relatively stagnant as discussed above. Optionally,rotation of the substrate is slowed or stopped to promote maintenance ofthis coating of liquid sulfuric acid composition on the substrate. Vaporcan be introduced into the apparatus either before, during, or after thestart of the dispense. Optionally, the dispense can be repeated toprovide a fresh supply of reactants to the wafer surface. Optionally,the wafer can be rapidly rotated between dispenses to cast off most ofthe sulfuric acid composition present on the wafer. Optionally, thewafer can be coated with a thin layer of sulfuric acid composition bymoving dispense duct 101 in a manner used in the semiconductor industryto create thin layers of resist.

In an embodiment of the present invention, the sulfuric acid compositionarrives at the wafer surface at substantially the temperature at whichit left dispense duct 101. In one embodiment, it may be beneficial tobreak the composition into small droplets that can absorb vapor and heatup before contacting the wafer. Such droplets can be created, forinstance, by atomizing the sulfuric acid composition with the vaporcomposition or with another gas, or by passing the sulfuric acidcomposition through a spray nozzle, or by other techniques. It may bebeneficial to move this source of heated sulfuric acid composition mistover the wafer.

In an embodiment of the present invention, the sulfuric acid compositioncan be preheated before it leaves the dispense duct 101 by contactingthe composition with a gas comprising water vapor. For example, a gascomprising water vapor could be combined with the sulfuric acidcomposition at a “T” in a heat resistant tube (eg. quartz). Thisembodiment offers the advantage that the sulfuric acid compositiontemperature attained can be much higher than the temperatures of theas-blended sulfuric acid composition or the vapor.

It will be appreciated that the various embodiments of the method asdescribed herein (such as variation in delivery of the sulfuric acidcomposition) are not limited to use with the specific apparatus of thefigures, but rather are applicable to use in all configurations oftreatment machines appropriate for use in carrying out the presentlydescribed methods.

The principles of the present invention will now be described inconnection with the following illustrative examples.

Experimental Techniques A. Sample Preparation

Wafer samples were prepared for evaluation of effectiveness of removalof ion implanted photoresist as follows:

-   -   200 mm diameter silicon wafers were coated with Shipley UV6 248        nm photo resist.    -   Some of the wafers were patterned and others were left with a        complete layer of resist (patterned and blanket wafers        respectively).    -   Samples of both patterned and blanket wafers were implanted with        arsenic at an energy of 40 keV, and with a dose of either 5×10¹⁴        or 1×10¹⁵ atoms/cm² (5E14 or    -   Approximately 2×2 cm fragments of resist coated wafers were        cleaved from full patterned and blanket wafers and attached near        the center of carrier wafers with high-temperature epoxy. Five        resist samples were typically attached to each carrier wafer:        blanket resist (no implant), blanket 5E14, patterned 5E14,        blanket 1E15, and patterned 1E15.

B. Evaluate Strip Efficiency

After processing, the samples were examined by bright field anddarkfield optical microscopy. Table 1 shows the evaluation criteria forboth blanket and patterned resist samples. The patterned samplesconsisted of various lithographic test patterns. Stripping of the arraysof fine lines on the patterned samples and of the blanket film served asmeasures of the stripping efficiency of a treatment.

TABLE 1 Score Explanation, Patterned Resist Explanation, Blanket Resist1 Gross lines and some blanket Only some undercut at edges remaining ofsample 2 Some lines and blanket Whole surface of resist remainingdamaged 3 Significant fine lines remaining Some removal of resist 4 Fewfine lines remaining Small spots of resist remaining 5 No visibleresidue No visible residue (bright or dark field) (bright or dark field)

C. Chamber Temperature Measurements

The temperature of the liquid composition of sulfuric acid/hydrogenperoxide as cast onto the side wall of the processing chamber wasmeasured by temperature sensor 41. This temperature was recorded at onesecond intervals and provides a thermal history of the chambertemperature through the process.

D. On-Wafer Temperature Measurements

Measurements of the maximum on-wafer temperature were made by attachinglabels to the wafers with dots that changed color irreversibly atspecified elevated temperatures (TL-10 series from Omega Engineering,Stamford, Conn.). The labels were covered with a 0.7 mm glass sheetattached with high temperature epoxy for protection from the strippingchemistries.

E. Treatment Process

The wafers prepared in the manner described above were treated in aZETA® spray processing tool commercially available from FSIInternational, Inc., Chaska, Minn. under the following conditions:

-   -   1. The sample wafer was loaded in slot 13 of a 27 wafer carrier        cassette 20 and the other slots filled with bare wafers. This        cassette and a second balance cassette were loaded onto the        turntable 22. A second sample wafer was loaded into slot 15 if        needed.    -   2. The turntable 22 was rotated at 120 rpm and heated H₂SO₄        (110° C.) from the recirculation bath 50 was dispensed on the        wafers from both the center 36 and side 40 spray posts for 3        minutes at a flow rate of approximately 5 lpm. 50 cc/min of H₂O₂        was added to the flow during the last approximately 1 minute of        the dispense. This step served to both preheat and wet        completely the wafers.    -   3. The turntable was rotated at 120 rpm and a 900 cc/min flow of        a mixture of fresh sulfuric acid composition (H₂SO₄ and        H₂O₂—SPM) from the mixing manifold 90 was dispensed from the        center spray post 36 for 30 seconds. The H₂SO₄ was preheated to        95° C. by an inline IR Heater before the H₂O₂ was added. The        blend ratio of the SPM composition varied between treatments as        listed in Table 2.    -   4. The process continued as above in 3. for six minutes except        that, in the inventive treatments, approximately 8 lpm of 95° C.        DI water 44 was dispensed onto the turn table 22 to generate        water vapor    -   5. After a six minute rinse with DI water, the samples were        treated for 75 seconds with an 80° C. SC-1 solution (1:1:15 vol        ratio of NH₄OH:H₂O₂:H₂O).    -   6. The samples were rinsed in DI water and dried in N₂.

TABLE 2 Example Water Max on-wafer Max side bowl Treatment H₂SO₄/H₂O₂Vapor temperature temperature Protocol Blend Ratio Added (° C.) (° C.) 120:1 Yes 204 159 2 (comparative) 20:1 No 93 60 3 10:1 Yes 154 50 4(comparative) 10:1 No 62 37 5  5:1 Yes 126 45 6 (comparative)  5:1 No 7843 7 2.17:1  Yes 145 54 8 (comparative) 2.17:1  No 72 32

EXAMPLES Example 1

Treatment Process E from above was performed twice using a 101 blend ofSPM with and without the addition of water vapor (Protocols 3 and 4 fromTable 2). The temperature of the liquid cast off against the chamberwall was measured by the side bowl temperature sensor 41. FIG. 4 showsthe temperature profiles of the two treatments. In both cases, the 5 μmrecirculated flow of H₂SO₄ heated the side bowl sensor to approximately65° C. in the first three minutes of the treatments. From 3 to 9minutes, the sensor temperature of the “SPM” comparative example droppedapproximately 7° C. to near 58° C. In contrast, the “SPM+water vapor”inventive example rose by 60° C. to 125° C. during the same period. Theaddition of water vapor in the chamber significantly increased thetemperature of the cast off liquid.

Example 2

Treatment Process E from above was performed 8 times using the 8Protocols from Table 2. The maximum temperature of the cast off liquidfor each treatment was measured with the side bowl temperature sensor 41at the end of the SPM dispense step (e.g., the 540 sec. reading fromFIG. 4). Maximum on-wafer temperatures were measured with temperaturesensing labels. FIG. 5 shows the as-blended temperature of the SPM(calculated from FIG. 1) using H₂SO₄ preheated to 95° C. by an inline IRHeater, the maximum on-wafer temperature, and the maximum side-bowltemperature for each treatment. The temperature of the as-blended SPMrose with increasing H₂O₂ concentration (reduced H₂SO₄). The maximumon-wafer and side-bowl temperatures of the comparative examples alsorose with increasing H₂O₂ concentration, but stayed well below theas-blended temperature of the SPM.

In contrast, the inventive treatments with water vapor achieved on-wafertemperatures 50 to 100° C. higher than the comparative treatments. Theseinventive temperatures are also substantially higher than either thevapor temperature or the on-wafer SPM temperature in the comparativeexamples. (The comparative treatments represent the temperature of theSPM on the substrates prior to vapor exposure.)

Further, the temperature increase between comparative and inventivetreatments decreased with increasing H₂O₂ concentration. FIG. 6 showsthe temperature difference between the as-blended SPM and the maximumon-wafer temperature. The benefit of the inventive vapor processdecreases with decreasing H₂SO₄ concentrations. To achieve maximumon-wafer temperatures, high concentrations of H₂SO₄ are desirable.

It is also desirable to increase the temperature of the as-blendedliquid by increasing the pre-blend temperature of the H₂SO₄, the H₂O₂ orboth. One embodiment would utilize H₂SO₄ from a recirculation tankoperating at greater than 95° C.

Example 3

Treatment Process E from above was performed 8 times using the 8Protocols from Table 2. Carrier wafers with samples of patterned andblanket, 5E14 and 1E15 implanted resist were processed in slot 13 of thecassette. Table 3 shows the results of evaluating the samples per theguidelines in Table 1. In all cases, the comparative treatments(Protocols 2, 4, 6, and 8) failed to thoroughly remove the implantedresist and scored a “1” in all evaluations. In contrast, the inventivetreatments (Protocols 1, 3, 5, and 7) removed completely the patternedand blanket 5E14 resist scoring a “5” in all evaluations.

While performing far better than the comparative treatments, theseparticular protocols of the inventive process were not able to removecompletely the 1E15 implanted resists. Protocols 1, 3, and 5 performedsimilarly, nearly removing the patterned resist. Protocol 7 performedslightly better on the blanket resist, but far worse on the patternedresist. To achieve maximum strip performance, high concentrations ofH₂SO₄ are desirable.

TABLE 3 Example 5E14 ion im- 5E14 ion im- 1E15 ion im- 1E15 ion im-treatment plant on pat- plant on plant on pat- plant on protocol ternedresist blanket resist tern resist blanket resist 1 5 5 4 2 2(comparative) 1 1 1 1 3 5 5 4 2 4 (comparative) 1 1 1 1 5 5 5 4 2 6(comparative) 1 1 1 1 7 5 5 1 3 8 (comparative) 1 1 1 1

Example 4

A modified version of Treatment Process E from above was performed on1E15 blanket and patterned wafer samples. The process was as follows:

-   -   A 5 lpm flow of H₂SO₄ from the recirculation tank was dispensed        from the center and side spray posts in 4 segments: 45 sec. at        20 rpm clockwise turntable rotation, 45 sec. at 300 rpm        clockwise, 45 sec. at 20 rpm counterclockwise, and 45 sec. at        300 rpm counterclockwise.    -   A 1600 cc/m flow of 10:1 SPM (1500 of 110° C. H₂SO₄ from the        recirculation tank and 150 cc/m of fresh 20° C. H₂O₂) was        dispensed from the center and side spray posts in two segments:        120 sec. at 120 rpm clockwise, 120 sec. at 120 rpm        counterclockwise. 8 lpm of 95° C. water was dispensed on the        turntable to create water vapor.    -   A 1000 cc/m flow of fresh 9:1 SPM (900 of 95° C. H₂SO₄ and 100        of 20° C. H₂O₂) was dispensed from the center spray post in two        segments: 180 sec. at 120 rpm clockwise, 180 sec. at 120 rpm        counterclockwise. 8 lpm of 95° C. water was dispensed on the        turntable to create water vapor.        The combination of increased chemical exposure time, increased        temperature, and the reversing of rotation resulted in complete        removal of the patterned and blanket 1E15 implanted resist (all        scores of “5”).

Example 5

In some cases, no oxidant need be added to the sulfuric acid compositionas unimplanted or lightly implanted resist can often be removed by H₂SO₄alone. As an example, a 5 lpm flow of 95° C. H₂SO₄ from therecirculation tank was dispensed from the center and side spray postsfor 3 minutes at 120 rpm. This treatment removed completely unimplantedblanket resist.

All percentages and ratios used herein are volume percentages and volumeratios unless otherwise indicated. All temperatures recited are assumingan ambient pressure of one atmosphere. It will be understood that if thetreatment process is carried out at a different pressure, thetemperatures of the various components involved in the process can beadjusted accordingly. All publications, patents and patent documentscited are fully incorporated by reference herein, as though individuallyincorporated by reference Numerous characteristics and advantages of theinvention meant to be described by this document have been set forth inthe foregoing description. It is to be understood, however, that whileparticular forms or embodiments of the invention have been illustrated,various modifications, including modifications to shape, and arrangementof parts, and the like, can be made without departing from the spiritand scope of the invention.

1. An apparatus for removing material from a substrate, comprising a) atreatment chamber for receiving a substrate having a surface therein; b)a source of a liquid sulfuric acid composition comprising sulfuric acidand/or its desiccating species and precursors; c) a liquid sulfuric acidcomposition dispensing orifice fluidly coupled to the source of liquidsulfuric acid and positioned to dispense liquid sulfuric acidcomposition onto the substrate surface; d) a water vapor dispenserpositioned to dispense water vapor in the treatment chamber to exposethe liquid sulfuric acid composition to the water vapor in an amounteffective to increase the temperature of the liquid sulfuric acidcomposition above the temperature of the liquid sulfuric acidcomposition prior to exposure to the water vapor; wherein the watervapor dispenser will provide the water vapor to the liquid sulfuric acidcomposition so that at the time of exposure to water vapor, the liquidsulfuric acid composition has a water/sulfuric acid molar ratio of nogreater than about 5:1.
 2. The apparatus of claim 1, wherein the watervapor dispenser comprises a system for introducing hot water into thetreatment chamber.
 3. The apparatus of claim 1, wherein the water vapordispenser comprises a water vapor generator located externally from thetreatment chamber.
 4. The apparatus of claim 3, wherein the water vaporgenerator comprises a system for bubbling a gas through a column ofwater.
 5. The apparatus of claim 3, wherein the water vapor generatorcomprises a system for boiling liquid water.
 6. The apparatus of claim1, wherein the liquid sulfuric acid composition dispensing orificedispenses the liquid sulfuric acid composition in a continuous stream.7. The apparatus of claim 1, wherein liquid sulfuric acid compositiondispensing orifice dispenses the liquid sulfuric acid composition in aplurality of discrete pulses.
 8. The apparatus of claim 1, comprising arotating turntable having a center of rotation for positioning asubstrate thereon, and the liquid sulfuric acid composition is sprayedfrom a spraying post directed to spray the sulfuric acid composition atan angle that is off normal from the center of rotation of the rotatingturntable.
 9. The apparatus of claim 1, comprising a rotating turntablehaving a center of rotation for positioning a substrate thereon, and theliquid sulfuric acid composition is sprayed from a movable spraying postpositioned to spray the sulfuric acid composition at a varying anglerelative to the center of rotation of the turntable in a sweepingmotion.
 10. The apparatus of claim 1, wherein liquid sulfuric acidcomposition dispensing orifice is configured to dispense the liquidsulfuric acid composition as an atomized spray.
 11. A method for varyingdirection of a spray of a liquid from a three orifice nozzle, comprisingthe steps of a) providing a nozzle having i) a first orifice providedwith liquid from a liquid source under sufficient pressure to eject astream of liquid therefrom; ii) a first gas orifice provided with a gasfrom a gas source, the gas being provided at a regulated pressure toeject a stream of gas from the first gas orifice to at least partiallydeflect the stream of liquid; iii) a second gas orifice provided with asecond gas from a second gas source, the gas being provided at aregulated pressure to eject a stream of gas from the second gas orificeto at least partially deflect the stream of liquid; and b) adjusting thespray direction of liquid from the nozzle by modifying the flow of thegas streams of at least one of the first gas orifice and the second gasorifice to impart a direction to the stream of liquid from the centralorifice.
 12. The method of claim 11, wherein the spray direction ofliquid from the nozzle is changed during a treatment process bymodulating the flow of gas from the first gas orifice and the second gasorifice.
 13. The method of claim 12, where the spray direction of liquidfrom the nozzle is changed in a sweeping motion.
 14. The method of claim11, wherein the spray of a liquid is carried out in a wafer treatmentprocess.